The present invention relates to a two-stage master cylinder for initially providing a large volume of braking fluid for actuation of brake cylinders and a second stage for finer control after a certain pressure has been reached.
For most brake applications two single piston calipers are controlled by one master brake cylinder. In demanding brake environments additional brake cylinders at the caliper are used to increase the force exerted on the brake pad and these additional cylinders increase the volume of braking fluid that must be provided under pressure by the master cylinder. The larger volume of brake fluid can be provided by a larger piston in the master cylinder however once the brakes are applied such a large piston does not have the degree of feel and the actual force that an operator must exert on a large piston is relatively high. These factors control the range of brake pedal travel and determine the force that an operator must exert on the brake pedal. If a small piston is used the brake pedal travel distance is greater, however the actual force the operator must exert on the brake pedal is reduced. If a large piston is used in the master cylinder the extent of movement of the brake pedal is reduced but the force exerted by the operator is increased.
The present invention overcomes a number of these problems and provides a system that allows adjustment of the forces that occur during brake actuation and control of the brake pedal travel distance.